User: | Open Learning Faculty Member:
The organism that I plan to study is Vincetoxicum nigrum or Dog Strangling Vine. More specifically, the seed production of the vine.
Along the north/south length of my study area, I can find the vine growing in the densely vegetated area between the creek and the pathway on the west side of the study area as well as along the hill side, on the east side of the study area. I do not see it growing in any substantial way in the manicured grass area between the slope and the pathway, however it is possible that the vine is trying to grow there but is impacted by the grass cutting.
I have noticed that the vines in the densely vegetated area appear to be healthier and more productive than the vines growing along the slope. In the vegetation the leaves are stiff and the vines are tall, wrapping around many other plants and spreading out. On the slope, the leaves are wilted and soft. The vines do not grow as tall on the slope either. Event where a tree or bush provides a possible climbing aid.
A few things may be causing this difference in plant health. Perhaps the amount of sunlight on the slope is too high. Or maybe there is more nutrient available in the wooded area. During site observations, I noticed that the soil on the slope is very hard and dry whereas the soil in the wooded area is noticeably wetter. This is consistent along the north/south length of the study area. It is a common sight in the surrounding area to see large patches of Dog Strangling Vine growing in full sun, on slopes. The difference is probably not too much sunlight. I suspect that reduced water availability would impact the plants ability to perform transpiration, which as a result, would impact the level of nutrients brought into the plant, with the water, for growth and reproduction.
Considering the above, I hypothesize that differences in water availability are impacting the vines ability to grow and thrive. My prediction is that plants in drier soil will produce fewer seed pods.
Based on my hypothesis and prediction. The predictor variable is soil moisture and the response variable is the number of seed pods per plant. The number of seed pods would be counted on a numerical scale and so would be a continuous variable. Depending on the measurement device, soil moisture could be categorical – in the case where a moisture probe simply displays one of a discrete set of value: dry, moist, wet, etc..) or continuous – in the case where a moisture probe displays a spectrum of out puts ranging on a scale from dry to wet. In this case, the moisture probe in use displays a spectrum and so would be considered continuous.
Your predictor and response variables are clear and I like that you have considered making your predictor variable either categorical or continuous, as the practicalities of testing might make Categorical more effective. I might suggest clearer wording of the predicted response in your hypothesis – “grow and thrive”. This is a bit vague, and it might be better to be me specific – something like “increase seed production” – so that your hypothesis is clearer and falsifiable.